1. Field of the Invention
This invention relates to a vehicle control system and a method therefor, and more particularly to a system for electronically controlling vehicle operation and a method therefor which utilizes Fuzzy Logic or Approximate Reasoning.
2. Description of the Prior Art
Vehicle devices and mechanisms that formerly were always operated manually by the vehicle operator are, more and more, being controlled automatically. An example of such automation can be seen, for instance, in the technology described in Japanese Patent Publication No. 9740/1984, which discloses a cruise control apparatus.
Such conventional automatic control has employed various techniques including proportional control, proportional-plus-integral control and proportional-plus-integral-plus-differential control. In all cases, however, the control techniques have been premised on receiving physical quantities as input values. The physical quantities are represented numerically and input to the control system as parameters indicating states of vehicle operation, whereafter a control value for regulating the portion of the vehicle to be controlled is determined in accordance with prescribed rules. In this kind of control, however, it is impossible to include among the control factors things that are difficult to express clearly as physical quantities, such as the feelings, judgments and impressions of a human being. Moreover, since in the conventional control, all of the effort goes into maintaining the target control value, the control value has to be changed so frequently that there is no room to give attention to riding comfort and other human factors. Thus, while coming closer to being able to carry out control on a level with the manual operations of the average driver, the conventional control systems are unable to simulate the driving techniques of an expert driver in terms of safety, economy or riding comfort and enjoyment. One of the reasons for this is that, as stated above, the feelings, judgments, impressions and the like of the expert driver cannot be expressed as physical quantities and thus cannot be incorporated as control factors in the systems. For the same reason, the conventional control techniques are unable to respond to the difference or diversity in the feelings among individual drivers. As a result, it has not been possible to adequately give each individual driver a feeling of oneness with the vehicle, i.e. to give him the feeling that the vehicle is an extension of himself.
Moreover, in the conventional control system control rules have become increasingly detailed year after year. Thus, when a microcomputer is used in the system, it is disadvantageously necessary to employ a memory of large capacity.